package com.hgt.springcloud.lb.impl;

import com.hgt.springcloud.lb.LoadBalancer;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.stereotype.Component;

import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;

/**
 * 自己写的轮询是实现类
 */
@Component
public class MyLB implements LoadBalancer {

    private AtomicInteger atomicInteger = new AtomicInteger(0);

    public final int getAndIncrement(){
        //当前第几次
        int current;
        //服务下标
        int next;

        //模仿自旋锁
        do{
            current = this.atomicInteger.get();
            next = current >= Integer.MAX_VALUE ? 0 : current+1;
        }//类似于自旋锁  JUC
        while (!this.atomicInteger.compareAndSet(current,next));
        System.out.println("----------------------------第几次访问，次数next:"+next);
        return next;

    }

    //通过下标获取实例
    @Override
    public ServiceInstance instances(List<ServiceInstance> serviceInstances) {
        int index = getAndIncrement() % serviceInstances.size();
        return serviceInstances.get(index);
    }
}
